1. Field of the Invention
This invention relates to the conduit connector art and, more particularly, to a flexible conduit connector for high temperature and pressure systems encountered in jet aircraft applications.
2. Description of the Prior Art
The primary function of jet aircraft engines on jet airplanes is the propulsion of the aircraft. The jet engine is also used as a source of power and heat by the redirection of a portion of the hot compressed air, termed bleed air, through conduits to pressurize and heat the cabin, deice the wing and engine cowlings, and remove rain from the front windows. Most jet engines are also started by bleed air from small auxiliary jet engines located near the tail of the aircraft or in ground support units. This bleed air is directed from one main engine to another during the starting sequence through a series of conduits. In operation, an aircraft is subject to many forces which bend its structural components. Conduits carrying the heated gas from the jet engines are therefore required to bend with the other structures of the aircraft.
Numerous flexible joints have been developed for this purpose primarily of the ball socket type. U.S. Pat. No. 4,165,107 presents a recent example of this type of joint. A spherical socket is attached to one conduit which receives a spherical ball on another conduit. A second spherical socket inside the first spherical socket retains the ball between the two. A plurality of graphite buttons between the ball and second socket allows low friction angulation between the two connected conduits. A bellows inside the ball provides retention of the high temperature and pressure gas flowing through the conduits. As the pressures and temperature increase, the pressure inside the joint squeezes the ball portion against the socket portion making deflection increasingly difficult. Rapid wear of the sliding parts results producing early failure of the device. In addition, the location of the bellows inside the ball limits the geometry of the bellows to a relatively stiff configuration further increasing the force required to deflect the conduits in relation to each other.
Other types of joints utilize gimbals to secure one conduit to another such as illustrated in U.S. Pat. No. 3,907,337. Either a bellows or rigid sliding structure as shown in U.S. Pat. No. 3,907,337 is constructed around the gimbal to seal the high temperature and pressure gases flowing through the connector. Sealing rings, as shown in U.S. Pat. No. 3,907,337, provide a sliding sealing system which is subject to wear. In comparison with the U.S. Pat. No. 4,165,107 discussed in the previous paragraph, however, the problem in the U.S. Pat. No. 3,907,337 connector is the tendency for the seal to blow out instead of an increase in pressure at the sliding location. While the gimbal allows angulation between the conduits, the nature of the construction of the gimbal in U.S. Pat. No. 3,907,337 creates single sided shear forces leading to early failure of the gimbal. One gimbal portion is coupled to one end of an axle and the other gimbal portion is coupled to the other end of the axle. The pulling and pushing of one conduit in relation to the other during operation result in the bending of the axle and gimbal portions in the direction of the single sided shear forces. Eventually the multiple expansions and contractions of the joint cause the internal failure of the joint at the axle connections.